1. Field of the Invention
The present invention relates to a recording medium including a medium body holding data and a print layer extending on the surface of the medium body, and to a method of making the same.
2. Description of the Prior Art
Characters and/or figures are often printed on the surface of a substrate in an optical disk such as a compact disk (CD). The characters and/or figures are utilized to represent the content of a software recorded in the CD, for example. On the other hand, characters and/or figures are not printed on the surface of a substrate in a magneto-optical disk such as a MO disk and a mini disk (MD). The existing MO disks and MD disks are contained in a cartridge, so that the characters and/or figures are printed on the outer surface of the cartridge.
The magneto-optical disk of magnetic field modulation recording type, such as MD disk, utilizes a magnetic head in contact with or flying above the surface of a substrate in writing data into a magneto-optical recording layer. A constant distance should be maintained between the magneto-optical recording layer and the magnetic head because a variation in the distance induces a variation in the intensity of the applied magnetic field. The magnetic field of the varied intensity hinders an accurate establishment of data in the magneto-optical recording layer. The magnetic head may suffer from damages if the magnetic head collides against a step formed on the surface of the substrate. Data thus cannot be written into the magneto-optical recording layer. Steps should be avoided on the surface of the substrate in a magnetic recording medium such as a magneto-optical disk of magnetic field modulation recording type.
As described above, no print is applied on the surface of a substrate in a magneto-optical disk such as a MD disk. Only guiding grooves having the depth of 100 nm approximately are asperities formed on the surface of the substrate in a magneto-optical disk. These asperities fail to influence the sliding or flying property of the magnetic head. However, an magneto-optical disk without a cartridge may directly be mounted on the driving shaft of a spindle motor in the future. A removable magnetic recording disk may be utilized even in a magnetic recording disk drive such as a hard disk drive. These cases may require print of characters and/or figures on the surface of a substrate. A print layer having a predetermined thickness forms a step on the surface of a substrate in a magneto-optical disk. The step is supposed to hinder a stable sliding or flying of the magnetic head on or above the surface of the substrate. Data cannot normally be written into the magneto-optical recording layer.